Comparison devices



March 27, 1962 s c ETAL 3,027,070

COMPARISON DEVICES Filed June 17, 1957 MACHINE DRIVE 7 Sheets-Sheet 1 SCANNING aga 49 55 V CQMPARATOR 52 f g W 1 2 i45s7s9 -2 ACCT. 35884 \5 55 4 1: JOHN ANYBODY 5 U\ I23 MAIN ST 6 ANYWHERE, USA 7 J L a e a 5 e s 4 fig 3 2/5 |23456769K0 l ACCT 35884 6' 3 0 o INVENTORS.

5 J 65 JOHN ANYBODY MAX E. SALLNZH 7 00 \25 MNN 51: JOHN SMITH 9 0 0 ANYWHERE,USA BY 35 8 8 4- Mmm M Filed June 17, 1957 M. E. SALLACH ET AL COMPARISON DEVICES 7 Sheets-Sheet 2 SENSING REFERENCE FIRST I P CYCLE SIGNAL AND" I RESET GENERATOR CIRCUIT I 57\ CLAMP 4 7 83 7 I INTER aECOND AND gfg: cmcun' POWER CONTROL E SUPPLY MONITOR 2:

70- I: l INFORMATION: SENSING CONTROL RELAY cxRcun'sz; STORAGE- AMPL|F|ER GATE. CONTROL REGISTER CIRCUH' CIRCUIT 78 72 RECORD w- 'cmcurr 7/ I l -7 4/ RESET 6L0 F|G J1 g? 5A "H I +IH INVENTORS. MAX E. SALLACH JOHN SNHTH /3/ BY 38/ MW M M March 27, 1962 M. E. SALLACH ETAL COMPARISON DEVICES 7 Sheets-Sheet 3 Filed June 17, 1957 March 27, 1962 M. E. SALLACH ET AL 3,027,070

COMPARISON DEVICES Filed June 1'7, 1957 '7 Sheets-Sheet 4 FROM REGISTER 1 T Ta" 7 :aeo 1 5/4 I 363 INVENTORS. 1 MAX E. SALLACH JOHN l. SMITH POWER M44 Mam LINE 1 2/ March 27, 1962 Filed June 17, 1957 M. E. SALLACH ETAL COMPARISON DEVICES '7 Sheets-Sheet SENSING HEAD CONTACTS IOO-I IS AND SWITCH 352 SWITCH 355 SWITCH 502 SWITCH 2 I5 SWITCH 223 SWITCH 228 SWITCH 235 SWITCH 550 CLOS OPEN

CLO D OPEN C LOSED CLOS D OPE OPEN

OPEN

PEN

OPEN

CLOSED OPEN O IOZDBOIOSO 6O INVENTORS- MAX E. SALLACH JOHN I. SMITH BY Mada/w 90 I00 IIO I I50 I I I I 340350 360 March 27, 1962 M. E. SALLACH ETAL 3,027,070

COMPARISON DEVICES Filed June 17, 1957 7 Sheets-Sheet 7 INVENTORS.

sM IT H E. SALLAC H MAX. JOHN WWW or magnetizable tape.

United States Patent 3,027,070 COMPARISON DEVICES Max E. Sallach, Chesterland, and John I. Smith, Euclid,

Ohio, assignors to Addressograph-Multigraph Corporation, Cleveland, Ohio, a corporation of Delaware Filed June 17, 1957, Ser. No. 665,962 24 Claims. (Cl. 23561.7)

This invention relates to comparators; more particularly, the invention relates to a new and improved comparator for comparing serial numbers or like data from two or more sources and to methods of comparing serial numbers or similar information. The method and apparatus of the invention are. particularly advantageous when employed in a business machine of the kind which is controlled conjointly by two or more dilferent groups of business instruments and are therefore described in that connection.

Many different business operations, including printing of various forms and mailing strips, accounting operations, and other business procedures, are frequently carried out by means of machines which are actuated in accordance with information encoded upon individual business instruments. These business instruments most frequently take the form of thin but relatively stiff paper cards which carry the desired information in the form of punched-hole coding, although other business instruments on which the desired data is encoded in the form of magnetic or conductive marlc ngs or by other means may also be employed. In some instances, the control instruments may not be physically distinct but rather may comprise individual sectors of a continuous punched Machines of this kind are essentially automatic in operation and function. almost wholly under the control of the business instruments, the principal duty of the machine operator, during normal operation of the machine, being to supply the business instruments to the machine.

In some business machines of the aforesaid character, it is necessary to utilize more than one group of business instruments in the control of the machine. Thus, in some printing operations, some of the information relating to a given person or transaction may be carried on one business instrument whereas additional information concerning the same person or transaction may be encoded upon a second complete business instrument. The same technique is frequently employed in accounting operations, in which a master file and a current ledger card or the like may both be maintained with respect to a given account. In the operation of business machines of this kind, both groups of business instruments are utilized simultaneously in a single printing, accounting, or other business operation and it is essential that the two different groups of instruments be coordinated with respect to each other to assure proper operation of the machine.

Usually, where two or more groups of business instrument are employed to control the operation of a single business machine, the business instruments of the two groups are encoded with corresponding serial numbers; that is, each instrument in the first group is encoded with a given serial number and there is a second business instrument in the second group encoded with the same serial number. In addition, each card .of the first group is encoded to indicate that it belongs to that group and the same technique is followed with respect to the second group. This dual sequence encoding is frequently essential, inasmuch as operation of the particular business machine is usually predicated upon processing of the business instruments in sequence according to serial number (hereinafter referred to as the intra-group sequence) and in sequence according 3,027,070 Patented Mar. 27, 1952 to group (hereinafter referred to as the inter-group sequence).

In some applications, it is highly desirable that the business machine itself be capable of checking the business instruments by which its operations are controlled with respect to both inter-group and intra-group sequence as a normal part of the machine operation in order to minimize the effect of any change or interruption in the desired business instrument sequences. In other applications, a separate and independent sequence-checking device or comparator may be desirable. When the comparator is incorporated directly in the business machine, it is highly desirable that the machine perform the sequence-checking function as an incident to its normal operation, thereby avoiding any requirement for passing the business instruments through the machine twice in order to accomplish a single printing, accounting, or similar function.

Sequence checking in the past has been accomplished by relatively complex and expensive relay-actuated devices which add very materially to the cost of the business machine. Moreover, these previously known sequence-checking arrangements have been relatively expensive to maintain. In some instances, it has been found diificult to determine whether or not the sequence checking device is in good working order and therefore capable of carrying out its essential function in an effective manner.

A primary object of the invention, therefore, is the provision of a new and improved comparator suitable for use in a business machine of the kind which utilizes a plurality of groups of business instruments in predetermined intra-group and inter-group sequence.

A further important object of the invention is a new and improved method of comparing serial numbers or like data from two sources to determine the comparison status of the data.

Another object of the invention is a new and improved business instrument comparison apparatus which efiectively interrupts normal operation of a business machine in response to electrical signals indicative of lack of comparison in the serial numbers or other identification data or two or more individual business instruments.

A further object of the invention is a new and improved comparison apparatus which effectively interrupts the normal operation of a business machine in response to an electrical signal indicative of incorrect inter-group sequence presentation of otherwise identically coded business instruments to the machine.

An additional object of the invention is a new and improved method of comparing serial numbers or like data from two sequences which affords a positive indication of any changes, additions, or deletions in the identification of one business instrument as compared to another.

Yet another object of the invention is a new and improved business instrument comparison device which etfectively monitors its own operation to afford an indication as to whether or not the comparison device is functioning properly.

Another object of the invention is a new and improved comparator for a business machine of the kind which utilizes two or more groups of business instruments in predetermined inter-group and intra-group sequence, which comparator is simple and economical in construction and affords maximum protection against malfunctioning of its own components.

In one aspect, the invention relates to a comparator for a business machine of the kind which utilizes a pinrality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination. A comparator constructed in accordance with this aspect of the invention comprises a storage register including a plurality of storage elements; in the preferred embodiment, these storage elements are of the kind having a substantially rectangular hysteresis characteristic, such, for example, as magnetic cores which exhibit this type of hysteresis characteristic. The storage register further includes input circuit means including at least one set of input coupling elements individually associated with the storage elements and output circuit means comprising at least one set of output coupling elements individually associated with the storage elements. In the case of a magnetic core storage register, the input and output elements may comprise suitable windings on the magnetic cores. Sensing means are provided in the comparator for generating a first electrical recording signal which is representative of the identification data on a given business instrument and for applying that recording signal to the storage register input circuit to record the data in the register. Sensing means, which may be the same as the first-mentioned sensing means, are also employed to apply a second electrical recording signal, representative of the identification data on the neXt subsequent business instiument, to the storage register input circuit to develop a first comparison signal in the storage register output circuit whenever any additional data is recorded in the register. The comparator further includes means for applying a reset signal to the input circuit of the storage register; this reset signal is applied to the storage register in time coincidence with the second recording signal to develop a second comparison signal in the output circuit, thereby affording an indication of the deletion of any data initially stored in the register by the first recording signal. In order to avoid erroneous operation of the device, it is desirable that the reset signal be of substantially shorter duration than the second electrical recording signal. In addition, the comparator includes a control circuit or other control means coupled to the output circuit of the storage register and adapted to interrupt normal operation of the business machine in response to the comparison signals.

In another apparatus aspect, the invention relates to a sequence comparison apparatus for a business machine of the kind which utilizes a plurality of groups of business instruments in predetermined intra-group and inter-group sequence determined by sequence identification, data encoded upon the individual business instruments. .A comparison apparatus constructed in accordance with this aspect of the invention comprises a reference signal generator for generating a reference signal indicative of the desired inter-group sequence. Sensing means are coupled to the reference signal generator and are utilized to modify the reference signal substantially, as by interrupting it, whenever the business instruments do not correspond in inter-group sequence to the desired sequence. A comparison means is provided to compare the intra-group identification data on the business instruments and to generate a comparison signal indicative of the comparison status of the instruments in this respect. The comparison apparatus further includes control means, coupled to the reference generator and to the aforementioned intra-group data comparison means, for interrupting norm-a1 operation of the machine in response either to a comparison signal indicative of no comparison between the business instruments or to the modified reference signal.

In its method aspect, the invention relates to a method of comparing serial numbers or like data from two sources, such as two individual business instruments, in a storage register of the kind comprising a multiplicity of individual storage elements each electrically actuatable between a first stable state and a second stable state and an output circuit for generating electrical signals indicative of changes in state of any of the individual storage elements. The method of the invention comprises the following steps in the recited time relationship: First, an electrical recording signal representative of the data from the first source is applied to the registers, in accordance with a predetermined data code, to actuate selected storage elements from the first to the second stable state. Second, an electrical recording signal of predetermined magnitude and duration representative of the data from the second source is applied to the register in accordance with the same data code; this second recording signal also tends to actuate the storage elements from the normal to the second stable state. Consequently, a first comparison signal is generated in the aforementioned output circuit of the register if any data is recorded in the register which was not included in the data from the first source. Third, an electrical reset signal is applied to the register; this reset signal is of substantially shorter duration than the second recording signal and is applied to the register only during a predetermined fractional portion of the time interval in which the second signals are supplied thereto. This reset signal is applied to the storage elements in a sense tending to actuate the elements from the second stable state to the first stable state and is utilized to generate in the storage register output circuit a second comparison signal indicative of the absence of any data from the second data source.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, shows preferred embodiments of the present invention and the principles thereof and what we now consider to be the best mode in which we have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a schematic diagram of a business machine, in this instance a printing machine, of the kind which utilizes two or more groups of business instruments in predetermined in'tra-group and inter-group sequence;

FIG. 2 illustrates one common type of business instrument which may be employed in the business machine of FIG. 1;

FIG. 3 shows another type of business instrument suitable for use in the machine of FIG. 1;

FIG. 4 is a block diagram of a sequence comparison apparatus constructed in accordance with one embodiment of the invention;

FIG. 5 is a schematic wiring diagram of the sensing, recording, and reset circuits and the storage register of the comparator of FIG. 4;

F-IG. 5A is an explanatory diagram showing certain operating characteristics for the storage elements of the apparatus of FIG. 5;

FIG. 6 is a schematic wiring diagram of the control circuits, including the inter-group sequence comparison circuit, of the embodiment of FIG. 4;

FIG. 7 is a schematic wiring diagram of the machine control circuitry of the embodiment of FIG. 4;

FIG. 8 is a schematic wiring diagram of the power supply of the embodiment of FIG. 4;

FIG. 9 is a timing chart illustrating the sequence of operations employed in the embodiment of FIG. 4;

FIG. 10 illustrates another storage register which may be employed in a comparator constructed in accordance with the invention; and

FIG. 11 is a block diagram of another embodiment of the invention.

The business machine 20 illustrated the schematic diagram of FIG. 1 comprises a printing machine which utilizes at least two different groups of business instruments in a single printing operation. In the illustrated machine, the business instruments, in this instance the punched cards 21, are first intermixed with each other in predetermined intra-group and inter-group sequence. As indicatedhereinabove, the term intra-group sequence as used throughout this specification and in the appended claims refers to serial number marking or similar identification data which, when the groups are physically separated, serves to identify the position of the individual business instruments within the group. Corresponding serial numbers or other intra-group markings are used in each of the two or more groups of business instruments. The term inter-group sequence is used to refer to the sequence of the 'groups with respect to each other as they are employed in the machine operation. Thus, the cards 21 may be of two separate groups each of which may include a relatively large number of cards.

After the business instruments 21' have been mixed together they are stacked in a suitable card magazine or other initial processing station in the machine. This portion of the machine includes a conveyor, schematically indicated at 22, the conveyor being driven from a conveyor drive shaft 23 which in turn is driven by suitable gearing or other mechanical drive connection from a main drive shaft 24.

The next subsequent station in the business machine 20 comprises a sensing station 26 which may include an upper unit or upper pin box 27 and a lower pin box 28. The sensing station 26 may be of completely conventional construction and may include a multiplicity of electrically conductive sensing elements or pins 29 arranged in a pattern corresponding to the row and column pattern of a conventional business instrument code as will be explained more fully hereinafter in connection with FIGS. 2 and 3. The conductive pins 29 are arranged to make contact with a corresponding plurality of socket or contact members 30 whenever the sensing station is placed in operation, providing no obstruction is afforded in the sensing head preventing contact between the pins and the socket members. The socket members 30 are individually connected to a comparator device 44) whereas the mating pin members 29, in the illustrated embodiment, are grounded.

The business machine 20 of FIG. 1 further includes a scanning station 31 comprising a suitable scanning unit 32 and a scanning station conveyor 33. The conveyor 33 is driven from a suitable drive shaft 34 through a mechanical coupling such as suitable gearing which connects the shaft 34 to the main drive shaft 24. The scanning unit 32 is electrically coupled to the vibrator or other suitable reproduction device 35 of a printing station 36 included in the machine; the printing station 36 may further include a helical printing anvil 37 which is operated in synchronism with the scanning portion of the device 32, the drive means for this portion of the printing machine not being illustrated.

A print-receiving web 41 is fed through the printing station 36 from a supply reel 42 to a take-up reel 43, the take-up reel being provided with a suitable drive shaft 44 which is coupled in mechanically driven relationship to the main drive shaft 24 as by suitable gears or other conventional means. The principal machine drive controlling shaft 24 is illustrated at 45 in the drawing and is electrically connected to the comparator device 4%.

In operation, the business machine 26 feeds the cards 21 into the sensing station 26 from the initial position or magazine comprising the conveyor 22. Assuming that two groups of cards are employed, the machine may be constructed to print information from business instruments of both groups upon the print-receiving paper Web 41. The first card, which should be from group one of the business instruments, is sensed in the sensing station 26 to develop electrical recording signals representative of the serial number or other intra-group identification data on the card. This information is recorded in the comparator 40. At the same time, a further electrical signal representative of the inter-group identification data on the card is also developed in the sensing station and applied to the comparator. If this latter signal indicates that the card is from group one, as it is intended to be,

operation of the machine is continued and the card is fed to the scanning station conveyor 33.

At the same time that the first card is fed to the scanning station 31, a second card may be fed from the magazine into the sensing station 26. This second card is sensed in essentially the same manner as the first and electrical signals representative of the serial number or other intra-group identification on the instrument are supplied from the sensing station to the comparator 4%. in the comparator, this identification data is compared with that initially recorded in the comparator from the first card and, if the data are identical, the machine continues its operation and prints information from the first card upon the print-receiving web 41. If, on the other hand, there are any omissions, changes, or additions in the identification data of the second card as compared with the first card, the comparator 40 applies a suitable electrical signal to the machine drive 45 and stops operation of the business machine 20. This interruption in the normal operation of the machine informs the operator thereof that the second card is not properly grouped with the first card, thereby permitting him to remove the first and second cards from the machine and to again start the machine in operation to continue its printing function.

In addition, the sensing station 26 applies to comparator 40 a signal indicative of the inter-group identification data carried by the second card. If the second card is correctly identified as belonging to group two, the machine operation may continue uninterrupted. On the other hand, if the second card carries identification data relating it to the first group of cards, thus indicating that the card is out of the desired inter-group sequence, the comparator 40 acts to interrupt the operation of machine drive 45 and thus interrupts the normal operation of the machine.

Assuming that the cards are in the correct sequence, with respect to both intra-group and inter-group identification, the second card is subsequently transferred to the scanning station 31 wherein it is analyzed by the scanning device 32 to control the printing of further information upon the print-receiving Web 41. Meanwhile, the next business instrument or card 21 from the magazine of the machine is fed into the sensing station 26 and the identification data therefrom is applied to the com.- parator 40 to initiate the next cycle of comparison as before. After scanning operation is completed in scanning station 31, the cards are fed to a receiving stack 49 and may subsequently be separated into their normal groups.

It will of course be recognized that the basic business machine 29, as illustrated in FIG. 1, has been greatly simplified in regard to the mechanical and electrical construction thereof. With the exception of comparator 40, however, the several operational units of the business machine may be essentially conventional in construction and operation and accordingly need not be described in detail herein. Moreover, the particular types of control and operational units illustrated in FIG. 1 need not be necessarily adhered to. For example, the sensing device 26 is not restricted to the illustrated mechanical pin-type arrangement as described but may comprise a photoelectric scanning device or other similar apparatus capable of sensing the identification data encoded upon the business instruments 21 to generate electrical signals suitable for application to the comparator 40. The illustrated scanning and printing stations 31 and 36 may be essentially similar to those described in United States Patents 2,529,978Thompson, issued November 14, 1950, and 2,571,720Hunt, issued October 16, 1951, or may comprise any other suitable apparatus for printing or otherwise reproducing or utilizing the desired information from the business instruments.

FIG. 2 illustrates a typical business instrument of the kind conventionally employed to control printing, accounting, and other business machines. The business instrument 21A shown in this figure is encoded with suitable identification data in accordance with a decimal code, the data being arranged in the usual series of rows 51 and colums 52. In the data code employed on business instruments of this type, numerical information is indicated by a single aperture in one of the ten rows 51 for each column 52. Thus, as indicated by the apertures 53, the particular business instrument shown in FIG. 2 is encoded with the serial number 35884. In addition, the business instrument 21A is also provided with another aperture 54 in column 9 thereof which indicates that the business instrument belongs to a particular one of a plurality of different groups. Further information may be applied to the business instrument 21A in the form of printed matter to be reproduced in the course of a business operation as indicated in FIG. 2 by reference numeral 55.

FIG. 3 illustrates another form of busines instrument frequently employed in controlling business machines of the general type described hereinbefore in conjunction with FIG. 1. Like the record card 21A described in connection with FIG. 2, the business instrument 21B is a punched-hole record card encoded with suitable identification data representative of a serial number and a group number. In this instance, the data is arranged according. to a series of rows 61 and columns 62, but only six different rows are utilized. In this particular data code, the numerals 0, l, 3, 5, 7, and 9 are designated by single apertures in the similarly numbered rows 61. The numbers 2, 4, 6, and 8, however, are indicated by a combination of two apertures in each instance; one of these apertures is disposed in the row corresponding to the next smaller digit and the second aperture is placed in the 9 row. Thus, as indicated in FIG. 3, the card 213 is encoded with the same serial number 35884 as card 21A of FIG. 2. In addition to the serial number code apertures 63, the business instrument 21B is also provided with a suitable group identification coding as indicated by the aperture 64 in row 1 column 9. Further information may be applied to the business instrument in the form of printed material as indicated in FIG. 3 by reference numeral 65. As will be made apparent in connection with the description of the comparator apparatus of FIGS. 4-9, the preferred apparatus embodiment of the present invention is adapted to operate equally well with either of the two types of business instruments indicated by record cards 21A and 21B in FIGS. 2 and 3 without requiring any substantial change in the comparator apparatus.

FIG. 4 affords a block diagram of a preferred embodiment of the invention, insofar as its apparatus aspects are concerned. The comparator apparatus shown therein includes an information sensing circuit unit 70 coupled to a storage register 71; the information sensing circuits 70 may be considered to include the pin and socket contact elements of the sensing station 26 (FIG. 1) or may comprise the sensing elements of any suitable sensing device adapted to analyze code markings or apertures on business instruments. A recording circuit 72 and a reset circuit 73 are also electrically coupled to the storage register 71. The devices 70-73 comprise the basic inter-group sequence comparison unit of he comparator 40; these devices are illustrated in detail in FIG. and are described more fully in connection therewith.

The comparator apparatus 40 further includes a logical OR amplifier 75 which is electrically coupled to the output circuit of the storage register 71. Amplifier 75 is connected through a gate circuit 76 to a main relay control circuit 77, the output of the relay control circuit being applied to a main relay operating coil 78 which, as will be described hereinafter, serves as a principal control unit for controlling the operation of the business machine. The comparator apparatus further includes a reference signal generator 7% which is electrically coupled to the gate circuit '76 and which is also coupled to a control monitor 80 having an output circuit comprising a relay operating coil 81. The reference signal generator is further electrically connected to a pair of logical AND circuits 82 and 83 having their output circuits connected to one terminal of a relay operating coil 84. The input circuits of AND circuits 82 and 83 may also be electrically connected to an inter-group data sensing device 85 which may comprise a part of the sensing station of the business machine but which has been shown separately .from the information sensing circuits 70 in the block diagram because it performs a substantially different function in regard to control of the comparator apparatus. The input of reference signal generator 79, on the other hand, is coupled to a reset device 86 by means of a clamp circuit 87. The circuits 75-87 illustrated in the block diagram of FIG. 4 comprise the control portion of the comparator apparatus 49, including the inter-group sequence comparison circuit of the preferred embodiment, and are shown in detail in FIG. 6.

The comparator apparatus 40 illustrated in block dia- 'grain form in FIG. 4 further includes a third principal unit, the power supply 90. As indicated therein, power supply 99 is electrically connected to each of the circuits 72, 73, 75, 76, 77, 79, 80, S2, 83, and 86 as well as to the relay coils 81 and 84 as is described more fully hereinafter. A detailed schematic wiring diagram for the power supply is provided in FIG. 8.

The information sensing circuits 70A illustrated in FIG. 5, which comprise one column of the sensing elements of the business machine sensing station, may be very simple in construction and may comprise, essentially, a series of electrically conductive pins 109, 101, 102;, 1G3, 104, 105, 106, 107, 108, and 109' which are adapted to engage with the corresponding socket members 110-119 respectively. Thus, pins 109-109 and socket members 111-119 correspond to the individual sensing elements employed to sense a single column 52 on a record or business instrument of the type illustrated in FIG. 2, the pin and socket combinations being disposed in alignment with the individual data code rows 51 when the business instrument is located in the sensing station of the machine. As indicated hereinbefore, the sensing pins -109, which correspond to one group of the pins 29, FIG. 1, are grounded. The socket elements -119, on the other hand, are individually connected in circuit with the storage register 71.

Storage register 71 comprises several different stages, the number of stages corresponding to the number of different data characters employed for inter-group identification on the business instruments with which the comparator apparatus is employed. Thus, if five-numeral serial numbers are utilized for inter-group sequence identification, as described hereinabove in connection with FIGS. 2 and 3, five different stages are incorporated in the storage register 71.

The first stage 71A of the storage register includes six toroidal magnetic cores designated by the reference numerals 121, 123, 125, 127, and 129. Each of these magnetic cores is preferably fabricated from a material having a substantially rectangular hysteresis characteristic of the general type illustrated in FIG. 5A. In FIG. 5A, the flux density B for one of these magnetic cores is shown as a function of the magnetomotive force H applied to that core. Thus, the magnetic core has two stable states of magnetization 13d and 131 which are of opposite polarity. Assuming that the core is in the positive stable condition indicated by point application of a magnetomotive force in one direction, indicated as a +H force, cannot change the stable condition of the core; as soon as the electrical current producing the M.M.F. is cut off, the core returns approximately to its original point of stability 130. Application of a negative-going magnetomotive force of substantial magnitude, however, drives the core along the portion of the magnetization curve indicated by reference numeral 132 and, when this is cut 01f, the core goes to the second 9 or alternate stable state 131. Similarly, if the core is initially in stable state 131, application of a negative-going thereto does not change the magnetization state appreciably, whereas a positive M.M.F., if of sufficient magnitude, may induce a change to the first stable condition 130. This phenomenon is well known in the art and has been utilized in numerous applications, particularly in the field of computer devices.

A first series of electrical coupling devices 140, 141, 143, 145, 147 and 149 are individually associated with the toroidal cores 120, 121, 123, 125, 127, and 129 respectively; these coupling devices comprise individual coils wound upon the magnetic cores. Coil 149 is connected through a resistor 150 to the sensing contact member 110, the other terminal of the coil being connected to a conductor 152. Similarly, coil 141 is connected through a resistor 151 to contact member 111, coil 143 is connected through a resistor 153 to contact member 113, coil 145 is connected through a resistor 155 to contact member 115, coil 147 is connected through a resistor 157 to contact member 117, and coil 149 is connected through a resistor 159 to contact member 119. In each instance, the remaining terminal of the coil is connected to the conductor 152. In addition, coil 141 is coupled to contact member 112 through the diode 161 and coils 143, 145 and 147 are connected to contact member 114, 116 and 118 respectively through similar diodes 163, 165 and 167. Coil 149, on the other hand, is electrically coupled to contact members 112, 114, 116, and 118 through the diodes 162, 164, 166 and 168 respectively.

A second series of electrical coupling elements, sometimes referred to hereinafter as reset coils, are included in the storage register section 71A. This second group of coupling elements comprises the coils 170, 171, 173, 175, 177 and 179 wound upon cores 120, 121, 123, 125, 127 and 129 respectively. Each of these reset coils is connected in series with the others and in series with the remainder of the reset coils of the storage register as indicated by the reset coils 180, 181, 183, 185, 187, and

189 associated with cores 190, 191, 193, 195, 197 and 199 of the second stage 72B of the storage register. One terminal of the series-connected reset windings is grounded, the ground connection not being shown.

Storage register stage 71A further includes another series of electrical coupling elements which form a part of the output circuit of the storage register. These coupling elements comprise the coils 200, 201, 203, 205, 207, and 209 which are wound upon cores 120, 121, 123, 125, 127, and 129 respectively. One side of each of these output coils is grounded; the other side of each of the coils is connected through a pair of suitably oriented diodes to a negative-signal output conductor 202 and to a positive-signal output conductor 204.

As indicated in FIG. 5, the succeeding stages of the storage register are all essentially similar to stage 71A. Thus, stage 71B, in addition to the toroidal cores and reset windings described hereinabove, includes a series of input windings which are coupled to the sensing contact members of a further section 70B of the sensing station of the business machine. Stage 71B of the storage matrix also comprises a suitable series of output windings connected as before to an output circuit comprising the leads 206 and 208. Conductor 206 is connected in parallel with lead 202 of the previous stage, whereas lead 208 is connected to the previously described output conductor 204 of the first stage. Similarly, the input conductor 210 of the stage 7113 is connected back to the input conductor 152 of the first stage.

The recording circuit 72 of the comparator apparatus is shown in detail in FIG. and comprises a grid-controlled rectifier 212, preferably of the type conventionally designated as a thyratron. The anode 213 of tube 212 is connected, through a cam-controlled switch 215, to the input or recording lead 152 of storage register stage 71A, the corresponding lead 210 of stage 71B, and to the corresponding input circuit components of the succeeding stages of the storage register. Switch 215 is a conventional cam-controlled device having normally-open contacts, the actuating cam for the switch being indicated in the drawing by reference numeral 216. The operational cycle for the switch is described more fully hereinafter in connection with the timing chart of FIG. 9. The cathode 217 of thyratron 212 is connected to a source of negative operative potential 218 as is described more fully hereinafter in connection with the power supply schematic, FIG. 8. The screen electrode 219 of tube 212 is also returned to the negative potential source 218. The control electrode 220 of the thyratron 212, on the other hand, is connected to a second source of negative operating potential 221 through a resistor 222. In addition, a cam-operated switch 223 is provided to electrically interconnect the cathode 217 and the control electrode 220 of the thyratron 212. Cam switch 223, the operating cam of which is designated in the drawing by reference numeral 224, may be essentially similar to cam switch 215 and comprises a pair of normally-open contacts which are closed during a portion of the operating cycle of the machine as will be described more fully hereinafter in connection with FIG. 9.

The reset circuit 73 is essentially similar in construction to the recording circuit 72 and comprises a thyratron or other grid-controlled rectifier 225 having an anode 226 which is connected through a load resistor 227 and a camoperated switch 228 to the series-connected reset windings of storage register 71. The actuating cam for switch 228 is indicated in the drawing by reference numeral 229. The cathode 230 of tube 225 and the screen electrode 231 thereof are returned to the negative operating potential source 218, whereas the control electrode 232 is connected through a bias resistor 233 to the other negativepolarity source 221. The cathode and the control electrode of the reset thyratron are also interconnected by a cam-operated switch 235, the actuating cam being indicated at 236.

FIG. 6 affords a detailed schematic diagram of the principal control circuits of the comparator apparatus, including the inter-group sequence comparison circuits. As illustrated therein, the logical OR amplifier 75 comprises two triode sections 250 and 251. Triode 250 comprises the input stage of the amplifier, the control electrode 252 of the triode being coupled to the positivepolarity output signal leads of the storage register 71 by means of an input resistor 253. The cathode 254 of triode 250 is coupled to the negative-polarity output signal leads of the storage register through an input circuit comprising an input resistor 255, a coupling capacitor 256, and a bias resistor 257. The anode 258 of the triode is connected to a source of positive-polarity operating potential 259, included in the power supply of the comparator, through a load resistor 260.

The two stages of the amplifier 75 are coupled to each other by a coupling circuit comprising a coupling capacitor 261 and a resistor 262 connected in series between the anode 258 and the second control electrode 263. The grid circuit of tube section 251 further includes a bias resistor 265 connected between the junction of capacitor 261 and resistor 262 and a source of positive operating potential comprising terminal 266 of the power supply. Bias resistor 265 is bypassed by a capacitor 264. The cathode 267 of the second stage is grounded and the anode 268 thereof is returned to the positive operating potential source terminal 259 through a load resistor 269.

As indicated hereinabove in connection with FIG. 4, the logical OR amplifier 75 is coupled to the main relay control circuit 77. Thus, the anode 268 of the amplifier output stage 251 is connected to the control electrode 270 of a grid controlled rectifier or thyratron 271 included in the relay control circuit by means of a coupling capacitor 272 connected in series with a resistor 273 and a further coupling capacitor 278. The anode 274 of the thyraton 271 is connected through a resistor 275 to the positive operating potential terminal 259 of the power supply. The screen electrode 276 and the cathode 277 of thyratron 271 are connected to each other and to one terminal of the relay operating coil 78, which is returned to ground through a normally-closed solenoidoperated switch 361B. As indicated in FIG. 6, a capacitor 281 is preferably connected in parallel with the relay coil 78. The input circuit of the main relay control 77 also includes a biasing arrangement comprising a bias resistor 282 connected between the control electrode 270 and a source of negative operating potential comprising the terminal 283 of the power supply, the bias resistor being bypassed to ground by a capacitor 284.

The gate circuit 76 includes a diode section 286, the anode 287 of the diode being connected to the junction of resistor 273 and capacitor 278 and being further connected through a resistor 288 to a source of positive operating potential comprising the terminal 289 of the power supply. The cathode 290 of the gate diode, on the other hand, is by-passed to ground by a capacitor 291 and is connected through a resistor 292 to a terminal 293 which is common to the input circuit of the control monitor 80 and the output circuit of the reference signal generator 79.

The control monitor 80 includes a thyratron or other grid-controlled rectifier 295 having an anode 296, a cathode 297, a control electrode 298, and a screen electrode 299, the screen electrode being connected directly to the cathode 297, which in this instance is grounded. The anode circuit of the control monitor comprises a resistor 300 which is connected to the positive terminal 259 of the power supply through the relay operating coil 81 and a normally-open cam controlled switch 302. The operating cam which controls the switch 302 is designated by reference numeral 303. Preferably, a capacitor 304 is connected in parallel with the relay operating coil 81.

The control electrode 298 of the monitor thyratron 295 is coupled both to the reference signal generator 79 and to the logical OR amplifier 75. Thus, a capacitor 306 and a resistor 307 are connected in series between the common terminal of capacitor 272 and resistor 273 in the output circuit of the OR amplifier and the control electrode 298 of the monitor thyratron. A resistor 308 connects control electrode 298 to a voltage divider comprising a pair of resistors 309 and 310 connected between the reference signal generator terminal 293 and ground. A negative bias for the control electrode 298 of the monitor tube is provided by a resistor 311 which connects the control electrode to a negative operating potential source represented by the terminal 312 of the power supply.

The reference signal generator 79 is a conventional flipflop circuit including two triode sections 320 and 321 which may be incorporated in a single tube. The two sections are cross-connected to each other in conventional manner; that is, the anode 322 of triode 320 is connected to the control electrode 323 of triode 321 by a parallel R-C circuit 324 and the anode 325 of tube 321 is connected to the control electrode 326 of tube 328 through a similar parallel R-C circuit 327. Anode 325 is also connected to the output terminal 293. The two control electrodes 323 and 326 are connected to a source of negative operating potential represented by terminal 328 of the power supply through suitable bias resistors. The anodes of the two triode sections are connected to the positive potential source terminal 259 through suitable resistive loads.

The sensing cycle reset device 86 in the illustrated embodiment comprises a cam-controlled switch 330, one terminal of which is connected to a source of negative operating potential represented by the terminal 331 of the power supply. The other terminal of the switch 335 is connected, through a series circuit comprising a resistor 332 and a capacitor 333, to the control electrode 323 of triode section 321. Similarly, the switch 338 is con- 12 nected, through a series circuit comprising a resistor 334 and a capacitor 335, to the control electrode 326 of tube 320. The operating cam which controls the switch 330 is indicated in the drawing by reference numeral 336. Preferably, a capacitor 337 is connected in parallel with the cam-operated switch 338.

The clamp circuit 87 comprises a diode 339 which, with diode 286, may form one-half of a conventional doublediode vacuum tube. The cathode of the clamp diode 339 is grounded and the anode thereof is connected to the junction between resistors 333 and 334. A resistor 340 is connected in parallel with the diode 339 in conventional manner.

The two logical AND circuits 82 and 83 comprise the two sections 341 and 342 of a conventional dual triode. The control electrode 343 of tube section 341 is connected to the reference signal generator control electrode 323 through a resistor 344. Similarly, the control electrode 345 of the other triode section is connected to the control electrode 326 of the reference generator section 322 by means of a resistor 34-6. The two anodes 347 and 348 of triode sections 341 and 342 are connected to each other and are returned to the positive operating potential source terminal 259 through the relay operating coil 84. Preferably, a capacitor 350 is connected in parallel with the relay coil 84.

The cathode 351 of tube section 341 is grounded through a normally closed cam-operated switch 352, the operating cam for the switch being indicated by reference numeral 353. Similarly, the cathode 354 of tube section 342 is grounded through a normally closed cam-operated switch 355 controlled by an actuating cam 356. A sensing switch 358 is connected in parallel with the cam control switch 352 and a similar sensing switch 359 is connected in parallel with cam operated switch 355. The two sensing switches 358 and 359 comprise the intergroup sensing device 85 shown in FIG. 4.

FIG. 7 illustrates the circuit used in the present embodiment to interrupt operation of the business machine in response to changes in circuit conditions in the comparator apparatus. In this connection, it is assumed that the machine drive 45 (FlG. 1) includes a solenoid-operated clutch or similar control element which, when deenergized, interrupts operation of the machine. This principal control element is indicated in FIG. 7 by the coil 360 which is connected in series with a solenoid-operated normally-closed switch 78A across a suitable power line which normally energizes the coil 360 to permit continued operation of the machine. The switch or relay 78A, in turn, is controlled by the relay operating coil 78 (FIG. 6) which, when energized, operates to open the contacts of switch 78A and thereby de-energize the main operating coil 360. In addition, the machine drive circuitry included in the unit 45 comprises a relay operating coil 361 which is connected across the power line in series with a reset switch 362. Coil 361 is employed to control the contacts of a normally-closed switch 361A which is included in the cathode circuit of triode section 322 of the reference signal generator 79. Coil 361 also controls the operation of the solenoid-operated switch 36113 in the cathode circuit of the relay control device 77. The machine drive circuits funther include an indicator light 363 connected in series with a solenoid operated switch 81A, being controlled by the coil 81 in the output circuit of monitor (FIGS. 4 and 6).

The power supply for the preferred embodiment of the invention, as illustrated in FIG. 8, is essentially conventional in construction but has been shown in detail because certain of the control functions of the comparator are accomplished by switching means incorporated therein. Thus, the power supply comprises an input transformer 370 having a center tapped secondary, the primary winding of the transformer being connected to a suitable A.-C. source through a conventional switching and overload protection circuit. A negative-polarity operating potential source 371 is connected across the secondary of the transformer in the usual manner by means of the diodes or other suitable rectifiers 372 and includes the usual ballast tube and filter arrangements. A series of potential dividers are employed to afford the negative-polarity operating potential terminals 283, 312, 328 and 331 noted hereinabove in connection with FIG. 6. The two negative-polarity operating potential terminals 218 and 221 employed to supply the negative operating voltages to the reset and recording circuits (FIG. are also included in this portion of the power supply. In addition, this part of the power supply circuit includes the solenoid-operated switch 84A, the contacts of which are normally closed. This switch is controlled by the coil 84 in the anode circuit of the two logical AND circuits 82 and 83 (see FIGS. 4 and 6). In addition, a manually operable switch 373 is connected in parallel with switch 84A to afford a convenient means for interrupting operation of the business machine as is described more fully hereinafter.

The positive operating potential source of the power supply is generally indicated in FIG. 8 by reference numeral 375, and comprises a suitable filter network connected across the secondary of transformer 370 by means of the rectifiers 376. This portion of the power supply is also provided with the usual ballast tube and suitable filter circuits. The main B+ or positive operating potential source is included in this portion of the power supply and is represented by the terminal 259. The reduced-voltage positive terminals 266 and 289 are provided by suitable voltage dividers connected between terminal 259 and ground.

In order to understand the invention in its method aspects and the operation of the preferred apparatus embodiment of the invention described hereinabove, the starting conditions in the various circuits illustrated in detail in FIGS. 5-8 should be first considered. The timing chart of FIG. 9 is provided for this purpose. Thus, when the business machine of FIG. 1 is first placed in operation and before the first card or other business instrument reaches the sensing station 26, the cam-controlled switches 215, 223, 228 and 235 (FIG. 5) are all open and the recording and reset circuits 72 and 73 are therefore maintained in quiescent or non-conductive condition. Consequently, there is no output signal from the storage register 71 and no output signal from the logical OR amplifier 75. The main relay control circuit 77 is maintained non-conductive by virtue of the negative biasing potential applied to the control electrode 278 of thyratron 271 through the bias resistor 282. This belng the case, no appreciable current flows through the operating coil 78 in the cathode circuit of tube 271, the switch 78A remains closed, and the machine is permitted to operate. It may be assumed that the triode section 321 of the reference signal generator 79 is conductive and that, as a consequence, the triode section 342 of the AND circuit 83 is conductive, the tube sections 326 and 341 of circuits 79 and 82 respectively being biased to cut-off. Cam-controlled switches 352 and 355 are both in their norm-a1 closed condition, as indicated in the timing chart of FIG. 9, and the switch 302 is also in its normal closed condition. Since switch 392 is closed, the operating potentials on the tube 295 of monitor circuit 80 maintain the tube conductive and thereby maintain a substantial current flow through the operating coil 81, keeping switch 81A open to prevent lamp 363 from being energized.

During the first sensing cycle in the operation of the business machine 20, the sensing head 26 is actuated to closed selected ones of the sensing circuits in accordance with the data encoded upon a record instrument in the sensing station. Thus, considering the sensing station section 70A in FIG. 5, and assuming that the particular card or business instrument in the sensing station is encoded as indicated by the examples provided in FIGS. 2 and 3, actuation of the sensing head in this first cycle of operation permits only the contact members 103 and 113 to engage each other, completing an electrical circuit to the input coil 143 on the toroidal core 123. This action does not, in and of itself, supply any electrical signal to the input winding 143, since the cam-controlled switches 215 and 223 in the recording circuit 72 are still open. At the same time, and again assuming that the business instrument is encoded in accordance with the examples of FIGS. 2 and 3, the inter-group sensing contacts 358 (FIG. 6) in the first AND circuit '82 are closed, indicating that the business instrument is of the first group or order.

Shortly after the sensing head is actuated to close the sensing contacts, the cam-controlled switches 352 and 355 in the two logical AND circuits 82 and 83 open. Under the conditions set forth hereinabove, -with the intergroup sensing contacts 358 closed, the opening of the camcontrolled switches 352 and 358 makes no effective change in circuit conditions in the two logical AND circuits 82 and 83; the cathode of the conducting tube 341 remains grounded through the alternate path provided by the contacts 358 and the non-conducting tube 342 remains nonconductive.

Shortly after the actuation of switches 352 and 355, the cam-controlled switch 302 in the anode circuit of the monitor opens, as indicated in the timing diagram of FIG. 9. This has no immediate apparent effect upon the monitor, since the capacitor 304 connected in parallel with coil 81 affords a suitable time delay in operation of the monitor circuit relay and prevents premature closing of the relay contacts 81A. Subsequently, the two camcontrolled switches 215 and 228 in the anode circuits of the recording and reset units 72 and 73 close, completing the anode circuits of these two devices. The two storage register control devices 72, 73 remain non-conductive, however, by virtue of the fact that the bias voltage applied to the control electrodes of the tubes from terminal 221 of the power supply is substantially negative with respect to the cathode potential as determined by connection to the power supply terminal 218.

Shortly after the anode circuits of the recording md reset devices have been completed, however, the cam-controlled switch 223 is actuated to close the circuit from control grid 229 to cathode 217 in the recording tube 212. Assuming, as before, that the sensing contacts 193 and 113 are closed, the closing of switch 223 in the recording circuit 72 renders the tube 212 conductive and thereby establishes a recording current through the input winding 143 on core 123 of the storage register. Assuming that the current through coil 143 is in a direction and of a magnitude such as to produce in core v123 a positive of the order of +2 as indicated in the explanatory diagram of FIG. 5A, core 123 is driven to the point 380 on its characteristic curve. If the core 123 was initially in its negative stable state 131, this change in the magnetic condition of the core produces a negative polarity signal pulse in the output winding 283 on the core and therefore supplies a negative impulse through lead 282 to the cathode circuit of the OR amplifier 75 (FIG. 6). This negative polarity impulse is amplified in tube section 250 and is amplified and inverted in tube section 251, producing a positive-going pulse in the output circuit in the OR amplifier. The postive polarity output signal from the OR amplifier is not applied to tube 271 with an amplitude sufficient to trigger the control tube into conduction, however, because the gate diode 286 is maintained conductive and effectively shorts out the input circuit of the control thyratron.

Referring again to FIG. 9, it is seen that cam switch 236 closes shortly after the cam switch 223 and therefore energizes the reset circuit 73 after energization of the recording circuit 72. The closing of switch 235 during this cycle of the machine, and during each subsequent cycle of the machine, establishes a current throughthe seriesconnected reset windings of the storage register 71 since, as indicated above, the other terminal of the reset Winding circuit is permanently grounded. The impedance of the reset winding circuit and the number of turns and direction of the reset windings in the storage register 71 are made such that each core is subjected to a negative M.M.F. having a magnitude of l as indicated in FIG. SA. Any of the cores in stable state 130 at the start of the comparison cycle are driven magnetically along the slope 13 2 of their magnetic characteristic to the point 381, thereby inducing a positive-polarity output signal in the output windings of those cores (FIG. 5). Considering the storage register section 71A as'an example, this positive polarity signal impulse is applied through lead 204w the logical OR amplifier 75, being supplied to the grid 252 thereof. As in the case of the negative polarity impulses applied to the cathode circuit by the recording operation,

however, this signal has no effect on operation of the business machine since the gate circuit comprising diode 286 prevents the'po'sitive polarity signal developed in the output circuit of the OR amplifier from rendering the main control tube 271 conductive. The positive-polarity output signals from the OR amplifier are, however, effectively applied to the monitor thyratron 295 to render that tube conductive. Thus, the thyratron 295 is reionized and supplies a substantial current to the relay coil 81, preventing closing of the switch 81A and therefore maintaining the signal light 363 in extinguished condition, In this connection, it should be noted that the cam switch 302, which initially opens to de-ionize and extinguish tube 295 before the recording and reset circuits 72, 73 are energized, closes just prior to energization of those circuits to permit reignition of the monitor thyratron.

Thereafter, in this first cycle of operation of the comparator apparatus, the two switches 352 and 355 in the cathode circuits of the AND amplifiers 82 and 83 are closed. Switches 236, 223, 228, and 215 open in the order indicated in FIG. 9 to de-energize the recording and reset circuits 72 and 73. After circuit conditions have thus been restored to their original status, the sensing head contacts open to permit transfer of the record instrument from the sensing head and to permit introduction of a new business instrument thereinto.

Subsequently, and before the next comparison cycle, the cam switch 330 closes momentarily, applying a negative-polarity electrical impulse to the two grid circuits of the reference signal generator 79. This signal, when applied to the grid circuits of the flip-flop 79, causes the circuit to change its operating conditions and renders tube 320 conductive, extinguishing tube 321. As a consequence, the tube 341 of the first AND circuit 82 is extinguished and tube 342 of AND circuit 83 is rendered conductive, thereby conditioning the comparator for its second cycle of operation.

In the second cycle of operation, the comparator apparatus described hereinabove in connection with FIGS. 4-8 again operates in accordance with the timing sequence illustrated in FIG. 9'. The first important action is the actuation of the sensing head contacts; assuming that the second business instrument is encoded with the same serial number as the first instrument, as it should be, actuation of the sensing head again closes contacts 103 and 113 in the sensing section 70A. Since this second record instrument is from the second group, however, it is encoded differently with respect to inter-group identification; consequently, the sensing contacts 359 are closed and the contacts 358 remain open (see FIG. 6). Consequently, when switches 352 and 355 are opened, tube 342 of the AND circuit 83 is maintained in conductive condition and tube 341 remains non-conductive.

The recording and reset circuits 72 and 73 of FIG. 5 are again actuated in the desired sequence by operation of the cam switches 215, 223 and 228. Consequently, a positive magnetomotive force of +2 is again applied to the input coil 143. Since core 123 is already in the stable condition 130, however, the core does not change its magnetic state substantially and no appreciable electrical signal is induced in the output coil 203. The reset signal applied to the reset windings of the storage register is also ineffective to produce any substantial output signal, since no information is eifectively erased from the storage register. Consequently, no significant comparison signal appears in the output circuit of the OR amplifier 75, the thyratron 271 is not triggered into conduction, and the machine continues its normal operation.

In this cycle of operation, since there normally is no positive-polarity output signal of substantial amplitude from the OR amplifier, this signal cannot be relied upon tore-ionize tube 295 and maintain the monitor relay 81, 81A in its normal or open condition. The monitor thyratron in this instance is re-ionized by virtue of the connection of its control electrode back through terminal 293 to the anode of the reference signal generator section 321. Because tube 321 ismaintained non-conductive during this second cycle of operation, the anode of the tube is at a relatively high positive potential. Consequently, the monitor thyratron is re-ionized as soon as the cam control switch 302 re-closes. The connection of the cathode 290 and gate diode 286 to this same terminal 293 also maintains the gate diode non-conductive during the second cycle of operation. When the second or comparison cycle of operation has been completed, the cam switch 330 again closes momentarily, applying a negative electrical'signal to the control electrodes of the reference signal generator 79 to again condition the flip-flop circuit for operation in accordance with the first cycle as described hereinabove.

Thus, during normal conditions, in which the record instruments of the two groups proceed in pairs through the machine with matched serial numbers and in the proper inter-group sequence, the comparator apparatus has no etfect upon machine operation and permits it to continue uninterrupted. As soon as this relationship is disturbed in any way, however, either by any changes in the intra-group serial number identification or in the inter-group sequence of the instruments, the comparator functions to interrupt operation of the business machine 20 and permit the operator to correct the discrepancy in the business instrument sequence.

Thus, during the second cycle, a business instrument encoded with a serial number diiferent from that of the first instrument may be introduced into the sensing head of the machine. For example, the instrument may be encoded to indicate the numeral 4 in the first column of the serial number rather than the numeral 3 as indicated in the examples of FIGS. 2 and 3. Under these circumstances, when the recording circuit 72 is energized, a recording signal is applied to both of the input coils 143 and 149. The core 129 is driven magnetically from its stable state 131 to the point 380 on its magnetic characteristic (FIG. 5A), inducing a negative-polarity output signal in the output winding 209 of the storage register section 71A. This signal is amplified in the OR circuit 75 and appears as a positive-going signal in the output thereof. This positive-polarity comparison signal is applied to the input circuit of the control thyratron 271 since, as indicated hereinabove, the gate diode 286 is maintained non-conductive during the second or comparison cycle of operation. Consequently, tube 271 is ionized and supplies a substantial operating current to the main relay operating coil 78. Accordingly, the relay contacts 78A are opened, de-energizing the main operating coil 360 of the business machine clutch or other control component and machine operation is halted. This operation of course has no effect upon the monitor circuit 80, since the thyratron 295 in that circuit is reignited 17 upon closure of cam switch 302 even if no positive-polarity signal is available from OR amplifier 75.

It is also possible that the serial number on the second or comparison business instrument might not be encoded with any information in the first column thereof. This being the case, the recording signal supplied to the storage register section 71A is not effective to change the magnetic state of any core in that section and no negativepolarity comparison signal is supplied to the remaining circuits of the comparator apparatus to interrupt operation of the machine. Under these circumstances, however, the reset signal applied to the storage register from reset circuit 73 drives the core 143, which was established in stable state 130 in the recording of the data from the first card, to the point 381 on its magnetic operating characteristic, thereby inducing a substantial positivepolarity comparison signal in the output winding 243. The comparison signal is amplified in the OR amplifier 75 and applied to the main control thyratron 271 to ionize that tube and again actuate the main control relay 78, 78A to interrupt machine operation. It is thus seen that any change in the intra-group or serial number identification of the record instruments effectively actuates the comparator apparatus to interrupt operation of the business machine, regardless of whether that change represented an omission of previously recorded data from the first card or an addition thereto. Moreover, it is important to note that this effect is accomplished in a single cycle of operation of the business machine and the comparator apparatus and that no separate reset cycle is required to determine that any of the initial identification data from the first business instrument is changed, added to, or omitted on the second instrument.

It is of course possible that the serial numbers on a given pair of business instruments may be the same but the instruments may be reversed with respect to the desired inter-group sequence. Thus, the first card of a pair introduced into the sensing head of the machine may be encoded to indicate that it belongs to the second group rather than the first. Under these circumstances, the contacts 358 do not close during the first cycle of operation of the comparison apparatus and tube 341 of the AND amplifier 82 is not maintained conductive through out this operating cycle as it normally would be. As a consequence, the relay operating coil 84 is de-energized and the relay contacts 84A (FIG. 8) are permitted to close. Closing of the contacts 84A effectively shorts out the normal negative bias applied to the control electrode of the main control thyratron 271, thereby permitting that tube to become conductive without direct application of any positive-polarity ionizing signal. As before, when tube 271 becomes conductive, the current drawn through that tube and through control relay coil '78 opens the main control relay contacts 78A and halts machine operation. Similarly, if contacts 359 fail to close in the second or comparison cycle of operation, the negative bias on the main control thyratron 271 is effectively removed and the tube becomes conductive, thereby interrupting the operation of the business machine. The switch 273 is included in the power supply of FIG. 8 and is connected in parallel with the relay contacts 84A to afford a convenient means for utilizing the comparison apparatus circuitry to interrupt machine operation, since closure of this switch is also effective to ionize the main control tube 271 and thus stop the machine.

As indicated hereinabove, the monitor thyratron 295 is extinguished between each recording and comparison cycle of operation of the comparator and is reignited very shortly thereafter, the monitor relay 81, 81A being maintained closed during the non-conductive intervals by the delay action afforded by the capacitor 304. This monitor circuit, however, is effective to indicate rn-al-functioning of the comparator apparatus. For example, any failure of the power supply which results in the loss of B+ voltage at terminal 259 is effective to de-ionize thyratron 295,

thereby interrupting the current through the monitor relay coil 81. When this occurs, the relay contacts 81A are permitted to close, energiz ng the indicator light 363 to inform the operator that the comparison apparatus is not operating properly. Because the monitor thyratron 295 is re-ionized during the recording or initial cycle of operation only by the signal applied thereto from OR amplifier 75, the same effect is accomplished in the event of core register failure or of the failure of any principal component in the OR amplifier circuit. In this instance, the signal light 363 flashes on and off, since tube 295 is ionized during each second or comparison cycle of operation whether or not any signals from the OR amplifier are supplied thereto.

One of the important features of the invention resides in the method aspects of the inventive concept as distinguished from the apparatus aspects thereof. In this regard, the sequence of operations followed with respect to actuation of the storage register 71 is highly important.

As indicated in the foregoing description of operation of the preferred apparatus embodiment of the invention, the intra-group identification data from the first business instrument is recorded in the storage register by applying to the register an electrical recording signal representative of that data in accordance with a predetermined data code, the data code in this instance being determined by the circuit arrangements interconnecting the sensing head contacts -119 with the input coils 140, 141, 143, 145, 147 and 149 (FIG. 5). In accordance with conventional practice, the data thus recorded in the storage register could be compared with second and supposedly similar data by applying to the register a second electrical recording signal representative of the second data in a sense tending to erase the originally recorded information from the storage register. The comparison status of the data could then be determined by a third step requiring application of a reset signal to the storage register to ascertain whether or not any data remained recorded therein, which would indicate non-comparison between the two data sources or business instruments.

This conventional method of comparison, however, makes it necessary to add substantially to the complexity of the storage register and associated circuits. Thus, in order for the signals applied to the storage register to erase the data initially recorded therein, it is necessary either to reverse the direction of current flow through the input windings employed originally to record the first data in the register or to utilize a complete and different set of input windings for this purpose. Needless to say, either of these expedients adds substantially to the cost of the storage register or of the circuitry associated therewith.

Of further importance is the fact that adoption of conventional methods in the control of the storage register necessitates a three-cycle sequence of operations rather than the simple two-cycle method outlined hereinabove. Thus, the data from the first source must be recorded, after which the erasing or comparison signal must be applied to the storage register, and finally the reset signal must be applied thereto. If the reset operation is carried out before comparison, the entire arrangement is inoperative. Consequently, the operational sequence, where conventional methods are employed, is also considerably more complex than in the case of the inventive method.

It is the application of the reset signal to the storage register during a predetermined intermediate fractional portion of the recording operation which affords the very substantial benefits derived from the method aspect of the invention. The data from the first business instrument is recorded in the storage register in conventional manner. During a portion of this operation, any extraneous data in the register is deleted therefrom by the reset signal. The data from the second instrument is then, contrary to the usual practice, recorded in the storage register in the same manner as the first data, affording an indication only of the addition of data to the register and providing no comparison signal indicative of omission of data in the second recording step. A clear and positive indication of the omission of data is provided, however, by the resetting or erasure step which is carried out during the second recording operation of the comparator. This reset operation affords a positive indication of the existence of data in the register not representative of data from the second source or business instrument, since it is effective to erase any such data from the register and to develop a comparison signal therein indicative of the erasure operation. It does not, however, interfere with the second recording operation, since it is initiated only after the second recording signal has been applied to the storage register, is terminated before that second recording signal ends, and is of an effective amplitude small enough with respect to the second recording signal as to preclude erasure of any of the data represented by the second recording signal from the register. In this connection, it is important to note that in an electromagnetic storage register of the kind described hereinabove the effective amplitude of the recording and reset signals is determined by the ampereturns applied to the cores and not by the current values alone. For the same reasons, during the initial cycle of operating the reset signal effectively clears data left in the register from the preceding comparison cycle without interfering with the recording of new data.

The method of the invention makes it possible to utilize a single set of input windings or other coupling elements associated with the storage elements of the register for recording both sets of data in the register and thereby substantially reduces the complexity of the register circuitry and of the energizing circuits associated therewith. Moreover, the inventive method reduces the comparison operation to a two-cycle procedure, in which recording and erasing operations are both carried out during each cycle of operation. Consequently, the comparison operation is materially accelerated and the apparatus employed to carry out the comparison procedure is reduced substantially in cost and complexity. In effect, the inventive method entails transfer of a portion of the burden of comparison signal generation from the reset operation to the recording operation, since the second recording step is utilized to provide an indication of one type of change in the data and the reset step affords an indication of a different type of change in the data.

Returning again to consideration of the apparatus aspects of the invention, it should be noted that the storage register circuitry illustrated in FIG. eflectively records decimal-code data. in the storage register in accordance with. a binary code, using only six cores instead of ten. Further, the binary code selected for the illustrated embodiment is the same as that frequently employed in business instruments of the type illustrated in FIG. 3. Consequently, although the storage register and sensing arrangement shown in FIG. 5 is intended for operation with business instruments on which identification data is recorded in accordance with a decimal code (see FIG. 2) it can also be employed without substantial change in a machine using binary-code records of the kind shown in FIG. 3. For this purpose, it is only necessary to change the sensing contacts illustrated in sensing section 70A to afford six contact pairs corresponding to the rows 61 of the business instrument 213 (FIG. 3) and to connect those contact pairs to the storage register in the same manner as the original contact pairs 100110, 1011 1, 103 113, 105115, 107-117, 109119. The remaining contacts of the decimal-type sensing arrangement are of course eliminated. With this very minor modification, which simply entails connecting the storage register to a sensing head of the kind conventionally used in conjunction with record cards of the kind illustrated by business instrument 213, the comparator apparatus operates as described hereinabove. Accordingly, it is seen that the comparator apparatus of the invention may be standardized for use with two different and widely used business instrument codes, thereby affording a substantial manufacturing saving in the production of business machines intended for use with the different codes.

The following tables afford an example of the operating potentials, the tube types, and certain of the circuit components which may be employed in the preferred embodiment described hereinabove. It should be understood that this material is provided solely by way of illustration and in no sense as a limitation.

Operating Potentials Power supply Operating terminal: voltage, volts 218 221 Tube Complement Tube: Type 212 /2 2D2l 250 /2 12AU7 251 /2 12AU7 271 a 5696 286 /2 6AL5 321 /2 12AU7 322 /2 l2AU7 339 /2 6AL5 341 12AU7 342 /2 12AU7 Diodes 161-468 HD2257 Storage register output diodes HD2257 Resistors 222 megohms 1 227 kilohms l 233 rnegohms 1 253 kilohrns 2.7 255 do.. 2.7

257 do 1.8 260, 269 do 68 262, 265 do 220 273 d-o 6'8 275 do 10 292 -2 do 220 300 do 10 307 do 150 308 do 4.7 309 do 470 310 do 100' 344, 346 megohrn l Capacitors 256 microfarad 0.01 261 -2 do 0.00l 272 do 0.001 278 micro-microfarads 470 284 do 10-0 306 do 100 333, 335 a do 330 281, 304, 350 "microfarad" 0.25

stituted directly for any of the storage register stages of the previously described embodiment such as stage 71A of FIG. 5.

The storage register ScCtiO J 71C comprises.

' next stage of the register (not shown).

ten magnetic cores 409409 which are provided with a series of input coupling elements or windings 410-419, a series of reset windings 426-429 and suitable output windings 430-439. The input windings 410 are individually respectively connected to the contact elements 1 16 119 which, as in the previously described arrangement, are arranged for electrical connection to the further contacts 100-109.- The input coils are also connected to the recording circuit 72 as in the previously described arrangement. The reset windings 420429 are connected in series with each other and with the reset windings of the One terminal of the series string of reset windings is connected to reset circuit 73, the other terminal being grounded. As before, one terminal of each of the output windings in the storage register is grounded, the other terminal being connected through suitable diodes or other uni-directional circuit elements to the positive-polarity and negativepolarity output leads 204 and 202.

Operation of the storage register stage 71C of PEG. 10 is essentially similar to that of the previously described stage 71A except that a single storage element or core is provided for each number in accordance with a decimal code. This arrangement has the advantage of eliminating the requirement for use of the diodes 161468 employed in the input circuit of the binary code arrangement of FIG. 5. In this respect, the embodiment of FIG. 10 is less expensive than that of FIG. 5. At present, however, the storage elements of the register, with their associated windings, are substantially more expensive than diodes suitable for use in the encoding arrangement of FIG. consequently, the requirement for four additional cores may in many instances counterbalance any economy afforded by the elimination of the input circuit diodes. Operationally, the two storage registers are fully equivalent to each other when employed with a decimal-code card such as the business instrument 21A of FIG. 2 and, of course, the ten-core register section may be employed with a binary code arrangement of the kind set forth in connection with business instrument 218, FIG. 3 simply by leaving four of the cores disconnected from the input circuit. In general, however, at the present time the embodiment illustrated in FIG. 5 is more economical than that of FIG. and, since it is also considerably more compact, is preferred.

FIG. 11 affords a block diagram of a further apparatus embodiment of the invention. In the comparison apparatus shown therein, a storage register 459 is electrically connected to the information sensing circuits 451 and to a reset circuit 452. The output circuit of the storage register is coupled to a logical AND circuit 453 through an amplifier 454. A gate flip flop circuit 455 is also coupled to the input circuit of the logical AND device 453, the flip flop being electrically controlled by a gate trigger switch 456. The output of the AND circuit 453 is coupled to a control flip flop 457 which in turn is coupled to a main relay control circuit 458.

In this embodiment, a sensing cycle reset switch or other reset device 459 is electrically coupled to a reference signal generator 460 having two output circuits individually electrically coupled to the first and second logical AND circuits 461 and 462. A sensing flip flop or trigger circuit 463 is also coupled to each of the AND circuits 461 and 462 and is controlled in operation by means of a pair sequence sensing device 464. The output circuits of the two logical AND devices 461 and 462. are both connected to a relay operating coil 466 to control the relay contacts 466A. The two contacts of the relay 466A are connected individually to the contacts of a second solenoid-operated relay 467A. One of the pairs of relay contacts is connected to ground through a resistor 468 and a normally-closed reset switch 469, the

remaining contact being connected to the output circuit .of the relay control unit 458. Relay 467A is controlled 22 by means of an operating coil 467 incorporated in the anode circuit of the relay control device 458.

in operation, a business instrument is sensed in the sensing device 451 and electrical signals representative of the intra-group identification data thereon are applied to the storage register 450. After the first record card or other business instrument has been sensed, a second business instrument is sensed to develop a second group of recording signals which are also applied to the storage register 454). In this instance, the second group of recording signals are applied to the register 45%) in a sense opposite that of the first recording signals in order to erase the initial data recorded in the register to the extent that the data is coincident with the information on the second business instrument. Subsequently, the reset circuit 452 applies a reset signal to the register 459. In the event that the data from the two business instruments being compared is identical, no output signal is generated by the storage register 450 and this portion of the comparator apparatus does not operate to interrupt action of the business machine in which it is incorporated.

The gate trigger switch 456 is cam actuated or otherwise actuated to control the operation of the gate flip flop 455 and thereby control the logical AND circuit 453 by applying thereto an electrical signal indicative of the desired inter-group sequence of operation. If a signal is generated by the storage register and applied to AND circuit 453 from amplifier 454 in conjunction with a signal from circuit 455 indicative of the occurrence of a comparison cycle, the AND circuit is actuated to apply a suitable control signal to the relay control circuit 453 through the flip flop 457. Any other signals which may be generated in the output of the storage register 45% by the recording action of the information sensing circuits 451 cannot actuate the control circuit 458, since coincidence of signals from the register and from the gate flip flop 455 is required to actuate the AND circuit 453 in the input of the relay control circuit. As in the previous embodiment, the relay control circuit is employed to energize a main control switch in the business machine (see FIG. 7) and thereby interrupt operation of the business machine in the event of non-comparison between two record instruments which should carry similar identification data.

The sensing cycle reset device 459 and the reference signal generator 460 may be essentially similar to the corresponding circuits 86 and 79 of FIG. 4. As before, the reference signal generator is utilized to control operation of the AND circuits 461 and 462. In this instance, however, the two AND circuits require both the reference signal from generator 460 and a further signal from the sensing flip flop 463 in order to become conductive. The sensing device 463 may be controlled by any suitable pair sequence sensing arrangement actuated by suitable sensing contacts in the business machine.

When the sensing flip flop 463 is operating in phase coincidence with reference signal generator 460, thereby indicating that the business instruments are in correct intergroup sequence, a given one of the two AND circuits 461 and 462 is maintained conductive during each cycle of the machine, thereby maintaining a substantial current through the relay coil 466 to keep contacts 466A open.

Assuming, however, that the cards are out of sequence and that sensing flip flop 463 therefore operates out of sequence with respect to the reference signal generator during a given cycle, neither of the logical AND circuits 461 and 462 is rendered conductive and the relay coil 466 is thus de-energized. When this occurs, the relay contacts 466A are permitted to move to their normally closed condition, thereby effectively breaking the circuit connecting the anode circuit of relay controller device 458 to ground through resistor 460. As a consequence, the operating potential on the anode of the relay control circuit tube (not shown in detail) is substantially increased, the control circuit is rendered conductive, and coil 467 is energized, thereby interrupting operation of the machine. Thus, any discrepancy in inter-group sequence of the business instruments is also effective to prevent continued operation of the business machine. It should be noted that in both instances of actuation of the main relay control circuit 458, the contacts 467A are closed, thereby maintaining the relay control circuit 458 in conductive condition until such time as the manually actuated reset switch 469 is opened to break the anode circuit and restore the comparator to its normal condition.

Although the inventive concept has been described and explained in connection with comparison apparatus utilizing toroidal magnetic cores and suitable electrical windings associated with those cores to form the storage register, it should be understood that the invention may be carried out to substantially equal advantage, from an operational standpoint, by utilizing storage elements of the ferroelectric type. Thus, individual cores of the storage register may be replaced by ferroelectric capacitors. For best results, it is preferred that the storage elements exhibit a substantially rectangular hysteresis characteristic in operation, regardless of whether ferromagnetic or ferroelectric phenomena are relied upon for the storage operation. in the event that ferroelectric storage elements are utilized in the storage register, it will of course be recognized that the individual input, output, and reset windings described hereinabove would be replaced by suitable electrodes or electrode pairs associated with cores of the particular dielectric selected.

The intraagroup data comparison apparatus of the invention, comprising the information sensing circuits 70, the storage register 71, and the recording and reset circuits 72 and 73 may also be modified for operation in a system in which the record cards or other business instruments are not intermixed physically. For this purpose, an additional sensing station may be connected to the storage register as indicated by the sensing station section 70E in FIG. 5. This additional sensing station section may be essentially similar to the original sensing station section 70A if the second group of business instruments is encoded in accordance with adecimal code or may be arranged for operation in accordance with a binary code as shown in the drawing. In this manner, substantially dissimilar business instruments may be employed to control a single machine and may be compared with each other in the one comparator device. The same expedient may of course be adopted in the embodiment of FIG. 11. In an arrangement of this kind, of course, the inter-group sequence checking elements of the preferred comparison apparatus may be omitted, since there would be no question as to this factor where the business instruments are not intermixed.

Accordingly, the invention provides a new and improved comparator for continuously checking the intragroup and inter-group sequence of business instruments in a business machine utilizing a plurality of groups of such instruments in a single operation. The inventive method permits a substantial simplification of the apparatus required without sacrificing any of the control functions of the comparator and at the same time materially accelerates operation in that it permits eifective combination of the reset and recording operations. The comparator apparatus is relatively simple and inexpensive, despite the fact that it controls operation of the business machine in response to variations in both intra-group and inter-group sequence of the business instruments controlling that machine. The versatility of the comparator is apparent from the fact that it may be employed without substantial change for difierently encoded business instruments and, in the preferred embodiment, the comparator effectively monitors its own operation to aiiord a positive indication as to whether or not it is functioning properly.

Hence, while we have illustrated and described the preferred embodiments of our invention, it is to be understood that these are capable of variation and modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the foilowing claims.

We claim:

1. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of bistable storage elements, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined amplitude representative of the identification data on the business instruments to the input circuit means of the storage register to generate a first comparison signal in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying an electrical reset signal of predetermined amplitude to said input circuit means in time coincidence with a predetermined portion of the recording signals to develop a second comparison signal in said output circuit means indicative of the omission on one instrument of data on the preceding instrument; and control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to at least one of said comparison signals.

2. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of storage elements each having a substantially rectangular hysteresis characteristic, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage element; means, including data sensing means, for applying electrical recording signals of predetermined effective amplitude representative of the identification data on the business instruments to the input circuit means of the storage register to generate a first comparison signal in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying an electrical reset signal of predetermined efiective amplitude to said input circuit means in time coincidence with a predetermined portion of the recording signals to develop a second comparison signal in said output circuit means indicative of the omission on one instrument of data on the preceding instrument; and control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to either of said comparison signals.

3. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of bistable storage elements, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined effective amplitude representative of the identification data on the business instruments to the input circuit means of the storage register to generate a first comparison signal of given polarity, in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying a reset signal of predetermined effective amplitude to said input circuit means in time coincidence with a predetermined portion of the recording signals to develop a second comparison signal of opposite polarity in said output circuit means indicative of the omission on one instrument of data on the preceding instrument; and control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to comparison signals of either polarity.

4. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of magnetic cores each having a substantially rectangular hysteresis characteristic, input circuit means including at least one set of input windings individually associated with said magnetic cores, and output circuit means including at least one set of output windings individually associated with said magnetic cores; means, including data sensing means, for supplying electrical recording signals representative of the identification data on the business instruments to the input circuit means of the storage register to apply a magnetomotive force of predetermined amplitude to selected ones of said cores and generate a first comparison signal of given polarity, in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for supplying an electrical reset signal to said input circuit means in time coincidence with a predetermined portion of the recording signals to apply a magnetomotive force of predetermined lesser amplitude to the cores and develop a second comparison signal of opposite polarity in said output circuit means indicative of the omission on one instnument of data on the preceding instrument; and control means, coupled to said output circuit means, 'for interrupting normal operation of the machine in response to comparison signals of either polarity.

5. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of storage elements each having a substantially rectangular hysteresis characteristic, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined efiective amplitude and duration and representative of the identification data on the business instruments to the input circuit means of the storage register to generate a first comparison signal of given polarity, in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying a reset signal of predetermined lesser effective amplitude to said input circuit means in time coincidence with an intermediate fractional portion of the recording signals to develop a second comparison signal of opposite polarity in said output circuit means indicative of the omission on one instrument of data on the preceding instrument; and control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to comparison signals of either polarity.

6. A comparator tor a business machine of the kind which utilizes two groups of business instruments, each encoded with identification data, in predetermined intragroup combination, said comparator comprising: a storage register including a plurality of bistable storage elements, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined effective amplitude representative of the identification data on the business instruments to the input circuit of the storage register in time sequence to generate a first comparison signal of given polarity, in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying a reset signal of predetermined effective amplitude to said input circuit means in time coincidence with an intermediate fractional portion of the recording signals to develop a second comparison signal of opposite polarity in said output circuit means indicative of the omission on said one instrument of data on the preceding instrument; control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to comparison signals of either polarity; and a gate circuit, coupled to said control means, for rendering said control means inefiective to interrupt operation of the machine during alternate cycles of operation of the comparator.

7. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of bistable storage elements, input circuit means including at least one set of input coupling elements individually associated with said storage elements, and output circuit means including at least one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined amplitude representative of the identification data on the business instruments to the input circuit means of the storage register to generate a first comparison signal in the output circuit means of the storage register, indicative of the presence on one instrument of data not present on the preceding instrument; means for applying an electrical reset signal of predetermined amplitude to said input circuit means in time coincidence with a predetermined portion of the recording signals to develop a second comparison signal in said output circuit means indicative of the omission on one instrument of data on the preceding instrument; control means, coupled to said output circuit means, for interrupting normal operation of the machine in response to at least one of said comparison signals; power supply means electrically connected to said storage register and to each of the aforesaid means; and

a monitor circuit, coupled to the power supply means and to the output circuit means of the storage register, for providing a positive indication of failure of either of said means.

8. A comparator for a business machine of the kind which utilizes a plurality of groups of business instruments, each encoded with identification data, in predetermined intra-group combination, said comparator comprising: a storage register including a plurality of bistable magnetic core storage elements, input circuit means including only two sets of input coupling elements individually associated with said storage elements, and out put circuit means including only one set of output coupling elements individually associated with said storage elements; means, including data sensing means, for applying electrical recording signals of predetermined effective amplitude representative of the identification data on the business instruments to selected ones of one of said two 

